(a). Field of the Invention
The present invention relates in general to multi-path simulation, and more particularly to a system and method that employs a shielded anechoic chamber to avoid external electromagnetic interference (EMI), and divides a signal into multiple simulation signals to simulate the signal attenuation and delay during multi-path transmission.
(b). Description of the Prior Arts
In recent years, cellular phones and wireless local area networks (WLAN) are in widespread use with the rapid development of wireless communication technologies. In comparison with the signal transmission with a single physical path, the wireless signal transmission has an intrinsic multi-path phenomenon. The multi-path phenomenon means the wireless signal reaching the receiving antenna by two or more paths. The phenomenon results in the constructive or destructive interference, and phase shifting of the signal, caused by the refraction, and the reflection from objects, such as buildings and obstacles. The phenomenon exists in most real environments and would increase the complexity and instability of signal transceiving.
However, for the manufacturers of cellular phones, wireless local area networks, etc., the simulation of signal transceiving of their products is mostly performed in the environments whose testing conditions cannot be precisely controlled (e.g. open space). It is very hard to provide reliable testing reports for the products used in the real environments because external EMI and superfluous reflection paths cannot be avoided in these environments. Moreover, the testing operation may be limited by the space characteristics of these environments. In some cases, channel emulators are used to simulate the real environments, but they fail to test the important feature of antenna diversity since they operate in the cable mode and antennas of communication devices to be tested are bypassed. Therefore, there is an urgent need for a solution to simulate the multi-path phenomenon, thereby testing signal transceiving of the products in the real environments and then providing useful testing results for product development.
In view of this, the present invention provides a system and method for multi-path simulation that can avoid external EMI and superfluous reflection paths and operate without the limits of space for testing.